There are more reasons to lose weight than trying to fit into those skinny jeans relegated to the back of your closet. Being overweight raises the risk of various chronic health conditions that, over the long haul, reduce not just quality of life but longevity. For every five-point increase in BMI (body mass index), mortality from diabetes surges by 116 per cent, mortality from renal disease by 60 per cent and mortality from vascular disease by 30 per cent.

With stats so dramatic, it’s no wonder health care professionals recommend losing excess weight before it starts to affect health. And unlike the amount you might need to drop to get into those skinny jeans, losing even small amounts of weight can have a positive effect.

But weight loss isn’t the only way to ward off chronic disease. Exercise has a proven track record for boosting health and longevity, even if the numbers on the scale refuse to move. Given the efficacy of both approaches, could the combination of eating less and exercising more offer double the health benefits when compared to exercise or dieting alone?

A U.S. research team, who already reported that weight loss — through diet or exercise — resulted in similar improvements in reducing cardiovascular risk factors, decided to test the theory on a group of 52 overweight men and women. Dividing the group into three, the goal was a six to eight per cent weight loss over 12-14 weeks by diet, exercise or a combination of the two.

All three approaches to weight loss were designed to create an energy deficit of 20 per cent. Those in the diet-only group were expected to reduce their portion sizes and to replace high calorie foods and snacks with fruit, vegetables and whole grains. The exercise-only group was encouraged to engage in moderate to high intensity cardiovascular exercise daily. The diet-and-exercise group used both methods. All subjects were monitored throughout the study and their diet and exercise prescriptions adjusted so that everyone could realize the same degree of weight loss.

As per the study’s design, all three groups lost the same amount of weight, about seven per cent, which resulted in a similar decrease in fat mass (15 per cent) and waist circumference. And surprisingly, despite differences in how they lost the weight, all experienced the same 10 per cent decreased risk of developing cardiovascular disease.

“We hypothesized that calorie restriction and exercise would yield greater improvements in risk factors for cardiovascular disease than would similar weight loss from calorie restriction or exercise alone. However, the results did not support this hypothesis,” said the researchers. “A straightforward interpretation of the findings from the present study is that weight loss itself provides the major cardioprotective effect of calorie restriction and exercise and that the benefits do not depend on which approach to weight loss is used.”

But that doesn’t mean exercise is without its added benefits. The exercise-only group lost the weight without losing valuable muscle, compared to a 2.5 per cent and 1.6 per cent decrease in fat free mass in the diet-only and diet-and-exercise groups, respectively.

Also of interest is the difference in the amount of exercise and calorie restriction needed to realize the same weight loss in all three groups. The diet-only group decreased the number of calories they consumed by 32 per cent, compared to 27 per cent fewer calories consumed by the diet and exercise group. Meanwhile the exercise-only group realized their weight loss by burning 412 calories daily (about 7.5 hours of exercise a week) through exercise, almost double that of the diet-and-exercise group, who sweated off 217 calories a day (roughly 4.5 hours a week).

Worthy of consideration, too, is the short duration of the study and the fact that the results were measured only in terms of their ability reduce cardiovascular risk, offering a very narrow view of the potential health benefits of all three weight loss strategies. Extending the study over a longer period of time or until a more significant weight loss is achieved may indeed show that eating less and exercising more results in more significant health gains than exercising or dieting alone.

In addition, the diet-and-exercise group actually exercised less and ate more than the diet-only and exercise-only crowd, which could be why the results didn’t have more of an impact on cardiovascular risk. It may be that the necessary threshold needed for exercise to significantly influence health wasn’t reached in those who combined diet and exercise.

So what’s the best way to lose weight so that it has the maximum impact on health? The answer is: any way you think you can be the most successful. As for exercise, consider it a value-added opportunity in that it helps preserve valuable fat-free mass (muscle) and requires you cut back fewer calories to achieve the same results as dieting alone. Then of course there’s exercise’s ability to help you have more energy in the day, sleep better at night and improve your overall mood, something this study wasn’t designed to capture but makes life just that much better no matter what your weight.